Scaling and importing from blender to unity
A Blender unit is per default 1m. You can display this in edit mode by the Edge Info checkbox the units can be enabled in the Scene Tab.



In order to import it correctly into Unity drag and drop the .blend file directly to your asset folder in unity, materials will be automatically created. Textures need to be imported and assigned manually to the material slots.

Behind the scene Unity runs Blender and does an .fbx export. You could also  export the model manually. File -> Export -> .fbx for more control:
Note that the export dialog provides settings to scale and change orientation of the used coordinate system: